• Energy Research
• engineering and technology close
• 15. Life on land close
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Abstract Despite the significant growth in the number of published life-cycle assessments of biofuels, important aspects have not captured sufficient attention, namely soil carbon emissions from land use change (LUC) and uncertainty analysis. The main goal of this article is to evaluate the implications of different LUC scenarios and uncertainty in the life-cycle energy renewability efficiency and GHG (greenhouse gases) intensity of wheat-based bioethanol replacing gasoline. A comprehensive assessment of different LUC scenarios (grassland or cropland converted to wheat cultivation) and agricultural practices is conducted, which results in different carbon stock change values. The types of uncertainty addressed include parameter uncertainty (propagated into LC (life-cycle) results using Monte-Carlo simulation) and uncertainty concerning how bioethanol co-product credits are accounted for. Results show that GHG emissions have considerably higher uncertainty than energy efficiency values, mainly due to soil carbon emissions from direct LUC and N2O release from cultivated soil. Moreover, LUC dominates the GHG intensity of bioethanol. Very different GHG emissions are calculated depending on the LUC scenario considered. Conversion of full- or low-tillage croplands to wheat cultivation results in bioethanol GHG emissions lower than gasoline emissions, whereas conversion of grassland does not contribute to bioethanol GHG savings over gasoline in the short- to mid-term.

Biomass pre-treatment is a key step in achieving the economic competitiveness of biomass conversion. In the present work, an imidazole pre-treatment process was performed and evaluated using wheat straw and eucalyptus residues as model feedstocks for agriculture and forest-origin biomasses, respectively. Results showed that imidazole is an efficient pre-treatment agent; however, better results were obtained for wheat straw due to the recalcitrant behavior of eucalyptus residues. The temperature had a stronger effect than time on wheat straw pre-treatment but at 160 °C and 4 h, similar results were obtained for cellulose and hemicellulose content from both biomasses (ca. 54% and 24%, respectively). Lignin content in the pre-treated solid was higher for eucalyptus residues (16% vs. 4%), as expected. Enzymatic hydrolysis, applied to both biomasses after different pre-treatments, revealed that results improved with increasing temperature/time for wheat straw. However, these conditions had no influence on the results for eucalyptus residues, with very low glucan to glucose enzymatic hydrolysis yield (93% for wheat straw vs. 40% for eucalyptus residues). Imidazole can therefore be considered as a suitable solvent for herbaceous biomass pre-treatment.

Energy consumption is associated with economic growth, but it comes with a toll regarding the environment. Renewable energies can be considered substitutes for fossil fuels and may contribute to reducing the environmental degradation that the world is presently facing. With this research, we aimed to offer a broader view of the state-of-the-art in this field, particularly regarding coal and biomass. The main objective is to present a viable and sustainable solution for the coal power plants still in operation, using as a hypothetical example the Pego Power Plant, the last operating coal fueled power plant in Portugal. After the characterization of land use and energy production in Portugal, and more particularly in the Médio Tejo region, where the power plant is located, the availability of biomass was assessed and it was concluded that the volume of biomass needed to keep the Pego power plant working exclusively with biomass is much lower than the yearly growth volume of biomass in the region, which means that this transition would be viable in a sustainable way. This path is aligned with policies to fight climate change, since the use of biomass for energy is characterized by low levels of GHGs emissions when compared to coal. The risk of rural fires would be reduced, and the economic and social impact for this region would be positive.

Biomass can be envisaged as a potential solution to mitigate the problems that the extensive exploitation of fossil sources causes on the environment. Transforming biomass into added-value products with better calorific properties is highly desired. Thermochemical liquefaction can convert biomass into a bio-oil. The work herein presented concerns the study of direct liquefaction of Eucalyptus globulus sawdust. The main goal was to optimise the operating conditions of the process to achieve high bio-oil conversion rates. Studies were carried out to understand the impact of the process factors, such as the residence time, catalyst concentration, temperature, and the biomass-to-solvent ratio. The E. globulus sawdust conversion into bio-oil was achieved with a maximum conversion of 96.2%. A higher conversion was reached when the eucalyptus sawdust’s thermochemical liquefaction was conducted over 180 min in the presence of a >2.44% catalyst concentration at 160 °C. A lower biomass-to-solvent ratio favours the process leading to a higher conversion of biomass into bio-oil. The afforded bio-oil presented a better higher heating value than that of E. globulus sawdust.

Globalization as a mechanism to connect people at distance and share knowledge has been flourishing. Simultaneously, environmental degradation has been increasing, as reflected in global warming. Through three dimensions, the economic, the social and political, and two measures, de jure and de facto, this study provides a disaggregated analysis of the effect of globalization on the critical issue of global warming for 25 European Union countries from 1990 to 2016. To emphasize globalization, the countries analysed were evaluated by two measures of globalization, de jure and de facto, resulting in their classification as high or low globalized countries de jure and de facto. Furthermore, energy consumption, economic growth and efficiency were included in an Autoregressive Distributed Lag model performed with the Driscoll-Kraay estimator. Robustness was checked using a Feasible Generalized Least Squares estimator. The results revealed that, overall, globalization increases environmental degradation, with the de jure measure having greater influence on high-globalized countries and the de facto measure having greater influence on low-globalized countries. Bearing in mind the increase in worldwide emissions driven by globalization, practices such as the relocation of polluting industries from high globalized countries should be discouraged. Incentives to harmonize global environmental restrictions could contribute to decarbonization worldwide.

Islands are often considered excellent socio-ecological laboratories for testing the rapidity of global change since they experience the climate effects of sea-level rise faster than other areas. The Azores are a Portuguese volcanic archipelago located on the junction of the three tectonic plates: the Eurasian, the African and the North American plates. São Miguel, the main island of the Azores archipelago, hosts three active volcanoes, but the last significant volcanic eruption was the Capelinhos volcano on the island of Faial in 1957. Hence, the Azores offers the opportunity to assess insular risk awareness, facing both telluric and climate-related hazards. The key research question emerges from their natural situation: how does the local population perceive the threat of the natural hazards that occur in Azores? Because risks are socially constructed and depend on the uniqueness of territories, risk mitigation strategies must focus on the individual experiences of local dwellers, as a relationship between risk awareness and such strategies may be expected. To analyze this relationship, a web-based survey with a questionnaire including these variables was administered to a sample of Azoreans. The study aimed to assess risk awareness of the Azorean population and find a relationship between this and reported mitigation strategies. The results gave a preliminary insight into Azorean risk awareness of natural hazards and showed a significant positive relationship between risk awareness-raising activities and reported mitigation strategies. This is relevant information for municipalities and regional governments of areas with similar risk exposures, showing that, although risk awareness alone is not enough for measures to be implemented, it may be an important motivational first step for this to occur.

Water is a scarce resource in the Mediterranean region where adverse climatic conditions promoting water shortages tend to increase with climate change. Under water scarcity conditions and high atmosphere evaporative demand, the risks of decreased water quality, and land salinization are major threats to the sustainability of irrigated agriculture in this region. The assessment of the quality of irrigation water is increasingly important to ensure the maintenance of long-term salt balance at a crop, farm, and regional scale. This study is focused on the spatial and temporal variability of water quality for irrigation in the Alqueva reservoir (Southern Portugal). The assessment was performed every 2 months during a distinctive drought year (2017) and included inorganic ions (Na+, Ca2+, Mg2+, K+, NH4+, Cl-, F-, SO42-, NO3-, and NO2-), pH, and electric conductivity (ECW) of water. Sodium adsorption ratio (SAR) was calculated, and potential soil permeability problems were estimated. The assessment showed significantly higher values of the physicochemical parameters in the most upstream sites, located near tributaries inflows, and an upward trend in ion concentrations throughout the year, with significantly higher concentrations of Na+, Mg2+, Cl-, and SO42, registered through May to November, reflecting the severe drought felt in the summer, autumn, and winter. The evaluation of water quality for irrigation indicated a slight to moderate risk of reduced infiltration rates, which should be considered whenever sprinkler irrigation is used, mainly in fine-textured soils, which are prevalent in the irrigated area. The multivariate statistical approach, using principal component analysis and factor analysis, identified two principal components related to salinity and nutrient concentrations. The cluster analysis revealed three groups of similarity between samples pointing to a more time- than space-controlled pattern. Overall, the temporal dynamics of the water physicochemical parameters could indicate that an abnormal annual distribution of precipitation and temperature may distort seasonal differences. To prevent water and soil degradation, a more frequent assessment of the water quality should be considered, allowing for the selection of appropriate soil and water management measures in irrigated areas.